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Search Results: 1 - 10 of 462219 matches for " Ilia A. Solov'yov "
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Structure and properties of small sodium clusters
Ilia A. Solov'yov,Andrey V. Solov'yov,Walter Greiner
Physics , 2001, DOI: 10.1103/PhysRevA.65.053203
Abstract: We have investigated structure and properties of small metal clusters using all-electron ab initio theoretical methods based on the Hartree-Fock approximation and density functional theory, perturbation theory and compared results of our calculations with the available experimental data and the results of other theoretical works. We have systematically calculated the optimized geometries of neutral and singly charged sodium clusters having up to 20 atoms, their multipole moments (dipole and quadrupole), static polarizabilities, binding energies per atom, ionization potentials and frequencies of normal vibration modes. Our calculations demonstrate the great role of many-electron correlations in the formation of electronic and ionic structure of small metal clusters and form a good basis for further detailed study of their dynamic properties, as well as structure and properties of other atomic cluster systems.
Towards understanding of birds magnetoreceptor mechanism
Ilia A. Solov'yov,Walter Greiner
Physics , 2007,
Abstract: In the present letter we suggest a new theoretical model for a quantitative description of the magnetoreception mechanism in birds. The considered mechanism involves two types of iron minerals (magnetite and maghemite) which were found in subcellular compartments within sensory dendrites of the upper beak of several bird species. The analysis of forces acting between the iron particles shows that the orientation of the external geomagnetic field can significantly change the probability of the mechanosensitive ion channels opening and closing. The performed theoretical analysis shows that the suggested magnetoreceptor system might be a sensitive biological magnetometer providing an essential part of the magnetic map for navigation.
Mechanism of magnetic field effect in cryptochrome
Ilia A. Solov'yov,Klaus Schulten
Quantitative Biology , 2011,
Abstract: Creatures as varied as mammals, fish, insects, reptiles, and migratory birds have an intriguing `sixth' sense that allows them to distinguish north from south by using the Earth's intrinsic magnetic field. Yet despite decades of study, the physical basis of this magnetic sense remains elusive. A likely mechanism is furnished by magnetically sensitive radical pair reactions occurring in the retina, the light-sensitive part of the eyes. A photoreceptor, cryptochrome, has been suggested to endow birds with magnetoreceptive abilities as the protein has been shown to exhibit the biophysical properties required for an animal magnetoreceptor to operate properly. Here, we propose a concrete light-driven reaction cycle in cryptochrome that lets a magnetic field influence the signaling state of the photoreceptor. The reaction cycle ties together transient absorption and electron-spin-resonance observations with known facts on avian magnetoreception. Our analysis establishes the feasibility of cryptochrome to act as a geomagnetic compass in birds, gives insight into structural and dynamic design features required for optimal detection of the geomagnetic field direction, and suggests further theoretical and experimental studies.
Uncovering a Solvent-Controlled Preferential Growth of Buckminsterfullerene (C60) Nanowires
Junfeng Geng,Ilia A. Solov'yov,Wuzong Zhou,Andrey V. Solov'yov,Brian F. G. Johnson
Physics , 2009,
Abstract: The fullerene (C60) nanowires, which possess a highly unusual morphology featured by a prism-like central core and three nanobelt-like wings joined along the growth direction to give an overall Y-shaped cross section, have been studied. The experimental observation coupled with theoretical calculation have enabled us to elucidate both the role of the fullerene and of the solvent in the crystallization process, thus opening up an opportunity for the in-depth understanding of the crystal growth mechanism. More generally, the method developed in this work could be extended into understanding the growth of other inorganic nanowires that have both host and guest molecules involved in their crystal lattices.
Fragmentation pathways of nanofractal structures on surface
Veronika V. Dick,Ilia A. Solov'yov,Andrey V. Solov'yov
Physics , 2010, DOI: 10.1103/PhysRevB.84.115408
Abstract: We present a detailed systematical theoretical analysis of the post-growth processes occurring in nanofractals grown on surface. For this study we developed a method which accounts for the internal dynamics of particles in a fractal. We demonstrate that particle diffusion and detachment controls the shape of the emerging stable islands on surface. We consider different scenarios of fractal post-growth relaxation and analyze the time evolution of the island's morphology. The results of our calculations are compared with available experimental observations, and experiments in which the post-growth relaxation of deposited nanostructures can be probed are suggested.
On the applicability of jellium model to the description of alkali clusters
Anton Matveentsev,Andrey Lyalin,Ilia A Solov'yov,Andrey V Solov'yov,Walter Greiner
Physics , 2002, DOI: 10.1142/S0218301303001181
Abstract: This work is devoted to the elucidation the applicability of jellium model to the description of alkali cluster properties on the basis of comparison the jellium model results with those derived from experiment and within ab initio theoretical framework. On the basis of the Hartree-Fock and local-density approximation deformed jellium model we have calculated the binding energies per atom, ionization potentials, deformation parameters and the optimized values of the Wigner-Seitz radii for neutral and singly charged sodium clusters with the number of atoms N <= 20. These characteristics are compared with the results derived from the ab initio all-electron simulations of cluster electronic and ionic structure based on the density functional theory as well as on the post Hartree-Fock perturbation theory on many-electron correlation interaction. The comparison performed demonstrates the great role of cluster shape deformations in the formation cluster properties and the quite reasonable level of applicability of the deformed jellium model.
Evolution of electronic and ionic structure of Mg-clusters with the growth cluster size
Andrey Lyalin,Ilia A Solov'yov,Andrey V Solov'yov,Walter Greiner
Physics , 2002, DOI: 10.1103/PhysRevA.67.063203
Abstract: The optimized structure and electronic properties of neutral and singly charged magnesium clusters have been investigated using ab initio theoretical methods based on density-functional theory and systematic post-Hartree-Fock many-body perturbation theory accounting for all electrons in the system. We have systematically calculated the optimized geometries of neutral and singly charged magnesium clusters consisting of up to 21 atoms, electronic shell closures, binding energies per atom, ionization potentials and the gap between the highest occupied and the lowest unoccupied molecular orbitals. We have investigated the transition to the hcp structure and metallic evolution of the magnesium clusters, as well as the stability of linear chains and rings of magnesium atoms. The results obtained are compared with the available experimental data and the results of other theoretical works.
Conformational properties of neutral and charged alanine and glycine chains
Alexander V. Yakubovitch,Ilia A. Solov'yov,Andrey V. Solov'yov,Walter Greiner
Physics , 2004,
Abstract: We have investigated the potential energy surface for neutral and charged alanine and glycine chains consisting of up to 6 amino acids. For these molecules we have calculated potential energy surfaces as a function of the Ramachandran angles phi and psi. Our calculations are performed within it ab initio theoretical framework based on the density functional theory and also within semi-empirical model approaches. We have demonstrated that the excessive positive charge of the system influences strongly its geometrical and conformational properties. With increasing of the excessive charge amino acid chains become unstable and decay into two or more fragments. We have analysed how the secondary structure of polypeptide chains influences the formation of the potential energy landscapes. We have calculated the energy barriers for transitions between different molecular conformations and determined the ones being energetically the most favourable.
Fission of charged alanine dipeptides
Alexander V. Yakubovitch,Ilia A. Solov'yov,Andrey V. Solov'yov,Walter Greiner
Physics , 2004,
Abstract: In this work we have performed for the first time a systematic analysis of the dissociation and fission pathways of neutral, singly and doubly charged alanine dipeptide ions with the aim to identify the fission mechanism and the most probable fragmentation channels of these type of molecules. We demonstrate the importance of rearrangement of the molecule structure during the fission process. This rearrangement may include transition to another isomer or a quasi-molecular state before actual separation of the daughter fragments begins.
Two center multipole expansion method: application to macromolecular systems
Ilia A. Solov'yov,Alexander V. Yakubovich,Andrey V. Solov'yov,Walter Greiner
Physics , 2007, DOI: 10.1103/PhysRevE.75.051912
Abstract: We propose a new theoretical method for the calculation of the interaction energy between macromolecular systems at large distances. The method provides a linear scaling of the computing time with the system size and is considered as an alternative to the well known fast multipole method. Its efficiency, accuracy and applicability to macromolecular systems is analyzed and discussed in detail.
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